Caption: Venera 4, Soviet Venus space probe. Still from a film shot to illustrate the probe's mission. The probe has released a parachute, as it would later do in the latter stages of its Venus mission. The Venera series of probes were used to explore the planet Venus. Venera 4, launched in 1967, weighed around a ton and was designed to study the Venusian atmosphere. It braked on entering and deployed a parachute, then continued to transmit data until the signal was lost after falling to an altitude of 25 kilometres.